Sorry, I didn't mean it like that at all.
I applaud your efforts and appreciate you sharing your experience.

It's very valuable to those of us who still need to make decisions about it all.

Thank you for your comment I appreciate it.

One point I would make is users tend to view the effectiveness of batteries on their night time delivery. Based solely on that, then depending on the cost of the battery per KW it can appear to be a questionable expense.

As with most things, as I’ve already alluded to its more about the joined-up thinking of the complete system starting with the individual panel wattage generation. Secondly, its making sure the direction of them is optimised for maximum light capture throughout the whole day. A typical scenario would be, the battery depletes overnight but the following morning the sun is out and due to the positioning of some of the panels they immediately start generating power to the household and any excess starts immediately charging the batteries. As the day progresses there is some cloud cover but because of the early morning charge the batteries supplement the reduced panel output and later in the day when the clouds clear the panels return to charging the batteries while continuing to power the household including say a three-phase pool pump.

Given the correct number of panels and the correct installation of optimisers running in balanced strings there is normally enough daylight to fully charge the batteries and run the household on depleted sun (panels are not as dependent on full sunlight as they used to be).

In other words, providing a lot of thought is put in to the installation the measure of the battery delivery has to be taken over a twenty-four-hour period not just overnight.

The obvious question is, why aren’t all systems like this, the answer is quite simple, the cost and not enough space, users normally want the panels tucked up out of the way on the roof normally on a single elevation and secondly, it’s a lot more labour cost to spread the panels out, coupled with more panels and longer cable runs and extra expense in optimisers. Each panel needs it own optimiser at say 275 euro’s per panel plus an inverter that can handle more than the typical two strings. The inverters and extra strings are well worth it with or without batteries.

It does pay for itself especially given the number of days down here that are bright (as apposed to full sun) and the batteries probably make a contribution in the region of 260 to 280 days per year.

As I have said, it’s not for everyone and is an individual judgement call.

We're completing some work on the house so the consumption is a bit erratic. We're not using power all day but in a way it helps to show the example clearly. I'm showing some screenshots below to show how the PV and battery work together to make sure there is still no draw from the grid.

The graph above shows the house consumption with a peak between 12.30 and 14.30.. The battery (in purple) shows the partial supply to power the house because there was no substantial PV output.

This graph shows when the sun was out and it powered the house and allowed the battery to switch off.

This graph shows the PV charging up the battery. The morning peak was when the sun was out and it fully recharged the battery from overnight use. The later peak shows the PV fully recharging the batteries from the daytime use back to 100% ready for the overnight use again.

I've posted this to show when working out the cost efficiency of batteries you just can't calculate it on overnight usage.

That's really cool.
It would be interesting to see the different graphs and total panel and battery output after a year or so; maybe it would be possible to separate and work out how much the panels and battery earned for you.

Of course everyone will have different usage patterns.

You're right. Ive installed PV and battery systems in my houses in UK and Portugal, and in my camper van. As you say, 540Wp panels are just over EUR 100 at Leroy-Merlin. I think 5kWh batteries are about EUR 1500 just now. The inverter will cost about EUR 1,000. Cables, AC isolator, mounting for panels will be about EUR 500 depending on how you do it. So, for 8 panels, about EUR 4,000 plus installation labour, which is very little - two semi-skilled guys for a day, or do it yourself. The rest of that EUR 10,000 is their profit. Doing it this way you probably wont be selling your surplus power, but thats not a big loss, as they only offer to buy for 2 years, and with a battery and correctly sized system you wont have a lot of unused generation. Personally I would go for 10 panels and an 8 or 10kW nverter; one or two 5kWh batteries. You can always add more later. They are the expensive part.

IVA on components is set to rise from 6% to 23% at the end of June, unless the government jumps in with an extension to the low rates.
So for ditherers like me, it's time to get to it!

I was just checking on various bits; 600w panel from "obras360" (who I have bought material from in the past) is 80 Euros (!!!) This is so cheap that it's difficult to imagine that prices on this part of the system will drop much further, if at all. The panels used to be the expensive part, now they're the cheapest part of the system.
Inverters are coming down but slowly; battery costs continue to drop so it's hard to say whether it's time to buy them now or not.

Regarding the question I asked earlier in this thread about the economic viability of batteries at today's prices; it's still hard to pin down, but they now come with a 10 year warranty and supposedly will live through 6,000 cycles. That would be around 4 cents per kwh.
So, correctly sized, I think the answer is a yes.

Installers are all booked out (of course), however, you can make the invoice and pay the bill before the work is done, if you dare.

Also worth a mention; the IVA rate of 6% also applies to heat pumps and air conditioners (which are actually the same thing), until the end of June, when it goes up to 23%.

I got my panels and heatpump system just before the tax increase deadline. I did not but the battery or electronics yet.

Is that an "ATLANTIC" heat pump system?..they are excellent! Sometimes they can be a little noisy at the intake/exhaust ports so route them to a place where that won't be an annoyance. (That's if you are running it as a standalone system).

It's Samsung AE120RXYDGG... 3-phase 12kw output. I wanted a major brand that I could self-instal and they had a good price.

It came with a lot of bits and pieces, electronic sensors and controls. There's also a 100 liter buffer tank and a 300 liter domestic hot water tank.

So when the sun hits the massive solar array, everything can heat up. It's sized to work in winter, which means there will be a large excess in summer.
The bureaucracy is high, and the returns low for grid injection, so I'm not going to bother with that.

One guy I know makes hydrogen with his excess solar power. It's an idea; but I'm always waiting to hear an explosion from his place.